217 research outputs found

    NLO Corrections to Deeply-Virtual Compton Scattering

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    We have calculated the NLO corrections to the twist-2 part of the deeply-virtual Compton scattering amplitude. Our results for the transverse and antisymmetric parts agree with recent calculations by Ji and Osborne and by Belitsky and M\"uller. In addition we present NLO results for the longitudinal part of the amplitude.Comment: 8 pages, Latex. Error in polarised gluonic coefficient in Eq.(8) correcte

    Perturbative Part of the Non-Singlet Structure Function F_2 in the Large-N_F Limit

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    We have calculated MSˉ\bar{MS} Wilson coefficients and anomalous dimensions for the non-singlet part of the structure function F_2 in the large-N_F limit. Our result agrees with exact two and three loop calculations and gives the leading N_F dependence of the perturbative non-singlet Wilson coefficients to all orders in αS\alpha_S.Comment: 11 pages, including one figur

    Sensitivity to atypical mycobacterial antigens in patients with Crohn's disease

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    Twenty-two patients with Crohn's disease were investigated for the presence of delayed cutaneous reactions and precipitating antibodies to atypical mycobacterial antigens of Runyon's Groups I, II and III as well as standard PPD. The results obtained, when compared to the control groups, do not show an increased incidence of sensitivity to such antigens in patients with Crohn's disease. However, their potential relevance to the pathogenesis of this disorder remains to be determined.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44374/1/10620_2005_Article_BF02236026.pd

    The Status of Lattice Calculations of the Nucleon Structure Functions

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    We review our progress on the lattice calculation of low moments of both the unpolarised and polarised nucleon structure functions.Comment: 6 pages, contribution to 29th International Symposium on the Theory of Elementary Particles, Buckow, Germany, (29 August - 2 September 1995). 6 pages, Latex, requires espcrc2.sty, epsf.st

    Generalized parton distributions of the pion in chiral quark models and their QCD evolution

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    We evaluate Generalized Parton Distributions of the pion in two chiral quark models: the Spectral Quark Model and the Nambu-Jona-Lasinio model with a Pauli-Villars regularization. We proceed by the evaluation of double distributions through the use of a manifestly covariant calculation based on the alpha representation of propagators. As a result polynomiality is incorporated automatically and calculations become simple. In addition, positivity and normalization constraints, sum rules and soft pion theorems are fulfilled. We obtain explicit formulas, holding at the low-energy quark-model scale. The expressions exhibit no factorization in the t-dependence. The QCD evolution of those parton distributions is carried out to experimentally or lattice accessible scales. We argue for the need of evolution by comparing the Parton Distribution Function and the Parton Distribution Amplitude of the pion to the available experimental and lattice data, and confirm that the quark-model scale is low, about 320 MeV.Comment: 25 pages, 15 figures, added discussion of the end-point behavio
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